Classifications

• • A—HUMAN NECESSITIES
  • A23—FOODS OR FOODSTUFFS; TREATMENT THEREOF, NOT COVERED BY OTHER CLASSES
  • A23C—DAIRY PRODUCTS, e.g. MILK, BUTTER OR CHEESE; MILK OR CHEESE SUBSTITUTES; MAKING THEREOF
  • A23C21/00—Whey; Whey preparations
  • A23C21/02—Whey; Whey preparations containing, or treated with, microorganisms or enzymes
  • A23C21/023—Lactose hydrolysing enzymes, e.g. lactase, B-galactosidase
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N11/00—Carrier-bound or immobilised enzymes; Carrier-bound or immobilised microbial cells; Preparation thereof
  • C12N11/14—Enzymes or microbial cells immobilised on or in an inorganic carrier
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N11/00—Carrier-bound or immobilised enzymes; Carrier-bound or immobilised microbial cells; Preparation thereof
  • C12N11/18—Multi-enzyme systems
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P19/00—Preparation of compounds containing saccharide radicals
  • C12P19/16—Preparation of compounds containing saccharide radicals produced by the action of an alpha-1, 6-glucosidase, e.g. amylose, debranched amylopectin
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P19/00—Preparation of compounds containing saccharide radicals
  • C12P19/18—Preparation of compounds containing saccharide radicals produced by the action of a glycosyl transferase, e.g. alpha-, beta- or gamma-cyclodextrins
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P19/00—Preparation of compounds containing saccharide radicals
  • C12P19/20—Preparation of compounds containing saccharide radicals produced by the action of an exo-1,4 alpha-glucosidase, e.g. dextrose
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P19/00—Preparation of compounds containing saccharide radicals
  • C12P19/22—Preparation of compounds containing saccharide radicals produced by the action of a beta-amylase, e.g. maltose
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals

Definitions

• This invention involves an immobilized enzyme conjugate and a method of preparing such conjugate. More particularly, the enzyme is immobilized on a support of granular diatomaceous earth.
• Enzymes which are proteinaceous in nature and are commonly water soluble behave as biocatalysts, regulating many of the chemical reactions which occur in living organisms. Enzymes may also be isolated and used in analytical, medical and industrial applications. For example, they are used in the preparation of food such as cheese and bread as well as in the preparation of alcoholic beverages.
• enzymes are commonly water soluble as well as being generally unstable, they are subject to deactivation and are difficult to remove for reuse from solutions in which they are utilized. These difficulties lead to an increased cost in the use of enzymes in commercial scale operations due to the necessity for their frequent replacement.
• various methods for immobilization sometimes referred to as insolubilization
• This immobilization of the enzyme permits its reuse whereas it might otherwise undergo deactivation or be lost in the reaction medium in which it is used.
• These immobilized enzyme systems may be employed in various reactor systems, such as in packed columns and stirred tank reactors, depending on the nature of the substrate which is being biocatalytically reacted.
• the immobilization of enzymes can be effected.
• materials useful for immobilization of enzymes or cells containing enzymes are disclosed in U.K. Pat. No. 1,444,539.
• the enzymes or cells are treated with a water miscible solvent, such as acetone, dried and then treated with polyethylenimine and glutaraldehyde to make shaped bodies of a water insoluble structure.
• U.S. Pat. No. 3,796,634 there is disclosed an immobilization method which involves absorbing a polyamine onto the surface of colloidal sized particles.
• the polyamine is cross-linked with a conventional amine-reactive cross-linking agent, e.g. glutaraldehyde, and the resulting reaction product is treated with NaBH 4 to reduce the aldehyde groups and thereby prevent any covalent bonding between the aldehyde groups and the enzyme's amino group.
• the enzyme is absorbed onto the treated surface of the particle at a pH such that the colloidal absorbant bears a net electric charge opposite that of the enzyme molecules so that ionic bonding aids other non-covalent bonding forces.
• This patent describes the absorbant particles as ranging in size from about 50 to about 20,000 angstroms, preferably from about 100 to 200 angstroms in diameter, with the absorbant material being activated charcoal, hydroxyapatite, alumina C gamma, and bentonite.
• This system depends on charge interactions for binding the enzyme to the treated particles. This type of bonding is less desirable than the formation of covalent linkages because ionic interactions are susceptible to the environmental conditions relative to this type of linkage such as pH, ionic strength and temperature.
• Liu, et al disclose an immobilization method for lactase on granular carbon in Biotechnol. Bioeng. 17, 1695-1696, 1975 which involves absorbing p-aminophenol or 1-phenol-2-amino-4-sulfonic acid to the carbon. These absorbed compounds provide the amino groups with which glutaraldehyde reacts and in turn binds the enzyme.
• the amino group containing compounds mentioned are monomers which possess chemical and physical properties different from those of a polyamine such as polyethylenimine.
• U.S. Pat. No. 4,141,857 discloses a method for enzyme immobilization which involves treating an inorganic porous support material such as gamma-alumina having pore diameters of from about 100 to about 55,000 angstroms and a surface area of about 100 to 500 m 2 per gram with a solution of a water soluble polyamine and contacting the treated support material with a solution of a bifunctional monomeric material, e.g. glutaraldehyde.
• This treatment leaves the treated support material suitable for reaction with the enzyme so as to form covalent bonds between the enzyme and the pendant aldehyde groups.
• Example II of this patent there is described the preparation of an immobilized enzyme conjugate by treating porous alumina spheres sequentially with solutions of polyethylenimine, glutaraldehyde and glucoamylase.
• This invention provides a method of preparing an immobilized enzyme conjugate which comprises the steps of: (a) contacting porous, granular, diatomaceous earth with a solution of a polyamine compound having pendant amine groups to cause the polyamine to attach itself to the diatomaceous earth; (b) removing the solvent and any unattached polyamine dispersed therein from contact with the diatomaceous earth and contacting the thus treated diatomaceous earth with a solution of an amine reactive material which is a multifunctional aldehyde, a multifunctional organic halide, a multifunctional anhydride, a multifunctional azo compound, a multifunctional isothiocyanate or a multifunctional isocyanate to cause one of the reactive groups to react with the pendant amine groups and leave a pendant amine reactive moiety available for further reaction; and (c) removing the solvent and any unreacted amine reactive material dissolved therein from contact with the diatomaceous earth support and contacting it with a solution of at least one enzyme to be immobil
• an immobilized enzyme conjugate comprising porous, granular, diatomaceous earth having attached thereto the reaction product of a polyamine compound having pendant amine groups and an amine reactive material which is a multifunctional aldehyde, a multifunctional organic halide, a multifunctional anhydride, a multifunctional azo compound, a multifunctional isothiocyante or a multifunctional isocyanate whose unreacted amine reactive groups have been reacted with free amine groups of enzyme or enzymes to bind it thereto.
• GDE granular diatomaceous earth
• a very suitable GDE preferably has a particle size of from approximately -16 to +48 mesh on the U.S. sieve series. Pore dimensions will preferably range in radii from approximately 35 angstroms to 1000 angstroms, and surface area preferably ranges from approximately 20 to 60 m 2 /gram.
• porous granular diatomaceous earth used in the Examples below (supplied by Eagle Pitcher Ind., Inc.) is fairly inexpensive and has good mechanical strength, and stability on exposure to heat and to acidic or basic solutions. Its physical and chemical properties are as follows:
• polyamines suitable for use in the present invention include polyethylenediamine, a polyethylenimine such as, for example, polydiethylenetriamine, polytriethylenetetramine, polypentaethylenehexamine or polyhexamethylenediamine.
• Betz 1180® may be used. This is a water soluble copolymer of epihalohydrin and polyamine and is marketed by Betz Laboratories, Inc., Trevose, Pa.
• Other suitable polyamines are polymethylenedicyclohexylamine, polymethylenedianiline, polytetraethylenepentamine and polyphenylenediamine.
• Suitable solvents include, but are not limited to, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, t-butyl alcohol, acetone, methyl ether, ethyl ether, propyl ether, isopropyl ether, toluene, benzene, xylene, hexane, cyclopentane and cyclohexane.
• the polyamine treated GDE is next treated with a solution of a multifunctional amine reactive material such as glutaraldehyde; bis-diazobenzidine-2,2'-disulfonic acid; 4,4'-difluoro-3,3,'-dinitrodiphenylsulfone; diphenyl-4,4'-dithiocyanate-2,2'-disulfonic acid; 3-methoxydiphenylmethane-4,4'-diisocyanate; toluene-2-isocyanate-4-isothiocyanate; toluene-2, -4-diisothiocyanate; diazobenzidine; diazobenzidine-3,3'-dianisidine; N,N'-hexamethylene bisiodoacetamide; hexamethylene diisocyanate; cyanuric chloride and 1,5-difluoro-2,4-dinitrobenzene by contacting it with a solution preferably containing from approximately 1 to 100
• Suitable solvents include but are not limited to, methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, t-butyl alcohol, acetone, methyl ether, ethyl ether, propyl ether, isopropyl ether, toluene, benzene, xylene, hexane, cyclopentane and cyclohexane.
• the treated GDE is removed from the solution of amine reactive material and preferably washed several times with deionized water.
• the term "derivatize" is intended to represent the formation of a reaction product between the amino functional group of the polyamine molecule bound to the GDE and the pendant amine reactive moiety of the amine reactive material.
• Any enzyme containing an amino group capable of reacting with the pendant amine reactive moiety can be immobilized by this method.
• two or more enzymes can be coimmobilized. These enzymes include, for example, trypsin, papain, hexokinase, ficin, bromelin, lactic dehydrogenase, lactase, glucose isomerase, glucoamylase, chymotrypsin, pronase, acylase, invertase, beta amylase, alpha amylase, pullulanase, transglucosidase, glucose oxidase, pepsin, rennin and fungal protease.
• the derivatized GDE is mixed with a solution of the enzyme(s) to perfect the enzyme immobilization.
• the enzyme may be in an aqueous solution and/or a solvent compatible with the enzyme.
• the immobilization may be the batch type, or on an industrial scale, immobilization may be carried out in a columnar reactor. Removal of the GDE from the enzyme solution preferably with subsequent water washing provides the GDE immobilized enzyme suitable for use in biocatalytic conversions.
• Another desirable feature of this immobilization process is that a previously used GDE support can be reused for immobilization after regeneration by a simple process involving a base-acid wash.
• the used support is slurried in (1) water, (2) 0.5 N NaOH, (3) water, (4) 0.5 N HCl, and then (5) water. This property of the process is significant because it eliminates any disposal problem for the user and provides a potential economic savings as well.
• the diatomaceous earth particles are washed with water until clear and then suction deaerated.
• the polyamine preferably polyethylenimine (Mol. Wt. 500-100,000) in an aqueous solution, is then added to the washed GDE, preferably in a ratio of approximately 10 ml GDE to approximately 50 ml polyethylenimine (PEI) aqueous solution. Concentrations between approximately 0.1%-0.5% (w/v) of PEI aqueous solution have been successfully used, and more preferably, approximately 0.15 to 0.20% (pH measured at 9.0-9.9) of PEI (Mol. Wt. 40,000-60,000) aqueous solution is added to the GDE.
• the effective reaction time can range between approximately 0.5 to 8 hours at approximately 20° to 30° C. with gentle agitation, with a reaction time of between approximately 2 to 5 hours at room temperature preferred.
• the excess PEI solution can be removed by decanting and washing the amine treated GDE with water.
• glutaraldehyde When glutaraldehyde is used as a crosslinking agent, it is typically added to the PEI treated GDE in approximately the same volume ratio as was the PEI.
• Glutaraldehyde concentrations of approximately 0.1 to 1.0% (w/v) are effective in this immobilization process. The preferred concentration is approximately 0.25-0.7% (w/v) aqueous glutaraldehyde solution containing 0.05 M sodium bicarbonate for a desired pH of approximately 7.9 to 8.3.
• the glutaraldehyde-bicarbonate solution has a measured pH of 8.2.
• the crosslinking reaction is carried out at approximately 20°-30° C. for approximately 0.5 to 20 hours, preferably for approximately 2 hours at room temperature with gentle agitation. Any excess glutaraldehyde solution can be removed by decanting and washing the treated GDE with water.
• Enzyme immobilization can be carried out at a temperature between approximately 4° and 30° C., at a pH suitable for the particular enzyme being immobilized, for approximately 1 to 10 hours with gentle agitation. The preferred conditions involve 4 hours of agitation at room temperature.
• the immobilized enzymes thus obtained can be stored in water or suitable buffer solution preferably in the cold in a refrigerator, more preferably at 1° to 10° C., and even more preferably 4° C., until used.
• the catalyst support of the present invention has been found to be well suited to the immobilization of enzymes in general. Enzymes immobilized according to the present invention are substantially more thermally stable than solubilized enzymes or enzymes immobilized according to U.S. Pat. No. 4,438,196, and thus most importantly, the present invention is particularly suitable for use with heat-labile enzymes.
• the immobilized enzyme activity per ml support can be varied and controlled by the particle sizes of support and the degree of loading of enzyme(s).
• the immobilization procedure produces a linkage between the enzyme and the polymer absorbed to the granular diatomaceous earth that is unusually stable, and it has been found that the diatomaceous earth particle does not become coated and fouled by proteins or other substances when a crude solution of liquefied corn starch is passed through a bed of the immobilized enzyme.
• the activity of the enzyme or enzymes, either immobilized or solubilized was determined as follows.
• the assay was conducted at 50° C. using as a substrate 50 ml of 10% w/v Maltrin-150 (dextrose equivalent 10-12) corn starch obtained from Grain Processing Company, (Muscatine, Iowa) in 0.05 M acetate buffer at pH 4.2.
• the substrate and enzyme were placed in a shake flask and incubated for 30 minutes.
• the amount of glucose formed is estimated by the Glucostrate Method (General Diagnostics) whereby the initial rate (also called initial velocity) of glucose formed per minute is determined from regression analysis.
• One unit of enzyme activity represents the amount of enzyme which will produce 1 micromole of glucose (or glucose equivalent) in 1 minute under the conditions of each enzyme assay, and is reported in U/ml (units of activity per milliliter of support).
• the amount of sugar formed was determined by the Ferricyanamide Method as described by Ghuysen, et al, in Methods in Enzymology, Volume VIII, page 685, Academic Press, N.Y. (1966) in which glucose was used as the reference.
• GDE granular diatomaceous earth
• Glucoamylase was immobilized at room temperature by the following procedure:
• the pendant amine groups of the polymer attached to the diatomaceous earth were derivatized with glutaraldehyde by the addition of 500 ml of a 0.5% w/v glutaraldehyde solution made up in 0.05 M sodium bicarbonate which resulted in a pH of 8.2. The flask was gently agitated for 2 hours at room temperature.
• the glutaraldehyde solution was decanted and the treated diatomaceous earth washed with deionized water to remove unreacted glutaraldehyde.
• the result was a support comprising diatomaceous earth, polyethylenimine, and glutaraldehyde.
• the immobilized glucoamylase was found to contain 110 10 units of activity per ml of support.
• a sample of 50 ml of the immobilized glucoamylase thus prepared was packed in a jacketed glass column of 2.5 cm diameter and 100 cm height.
• 30% enzyme liquefied starch (40 DE) (23.63% glucose, 10.99% maltose, 0% isomaltose; degree of polmerization: DP 3 13.10%, DP 4 7.10%, greater than DP 4 45.18%), pH 4.2 buffered with 5 mM acetate, was fed continuously to the column at various flow rates. The temperature of the column was kept at 50° C.
• the products were analyzed by HPLC (high pressure liquid chromatography) and GC (gas chromatography). The results are given in the following table.
• a maximum glucose level as high as 96.6% can be reached verifying that a dextrose level similar to soluble glucoamylase saccharification can be obtained.
• This high level of dextrose at 30% DS indicates that the enzyme is at or very near the surface of the particle such that internal diffusion is not a major factor influencing the reaction.
• the high sugar fraction >DP 3
• glucoamylase bound to GDE is capable of hydrolyzing starch more completely than glucoamylase bound to granular carbon.
• Maximum dextrose of about 96% is reached by glucoamylase bound to GDE and about a 95% level with glucoamylase bound to carbon.
• the increased dextrose yield may indicate that the AG bound to GDE is less sterically hindered or is bound more at the surface of the particle so that the substrate experiences less diffusion resistance.
• Another indication of less diffusion resistance with glucoamylase bound to GDE is the lower level of isomaltose formed at the respective dextrose level.
• Immobilization of glucoamylase was repeated in the same manner as in Example I with variation of the particle size of the GDE, and of the amounts of glucoamylase immobilized to compare the activity of the glucoamylase to the amount of the glucoamylase.
• EXAMPLE IV A 100 ml quantity of PEI-glutaraldehyde derivatized GDE as in Example I (but made with -24 to +48 mesh GDE) was used to immobilize soy beta-amylase (Hi-maltosin S, Hankyu Kyoei Bussan Co., Ltd., Osaka, Japan).
• the enzyme solution used for treating the derivatized GDE was 1 gram (40,000 units/gram) of the soy beta-amylase in 500 ml of 0.02 M phosphate buffer at pH 7.0.
• the immobilization procedure was carried out as in Example I.
• the immobilized beta-amylase thus obtained was assayed (pH 5.5) at 134 units per ml support.
• the thermal stability of the ⁇ -amylase bound to GDE was dramatically increased. After 1 hour, essentially no loss in activity was observed for the GDE immobilized enzyme, but less than 60% of the carbon immobilized enzyme activity and less than 20% of the soluble enzyme activity remained. Even after three hours at 60° C. over 85% of the GDE immobilized ⁇ -amylase was still active compared to less than 45% of the carbon immobilized enzyme and less than 5% for the soluble enzyme.
• a 100 ml quantity of derivatized GDE as in Example I was used for the immobilization.
• the derivatized GDE was treated with 500 ml of a pH 6.0 buffer solution (0.1 M acetate) containing 12,000 units of glucoamylase (Diazyme L-200, Miles Laboratories, Inc.) and 12,000 units of pullulanase (Promozyme® 200L, Novo Ind., Inc.), by which the enzymes were coimmobilized on the porous GDE support by the method described in Example I.
• the coimmobilized glucoamylase-pullulanase composite thus obtained was assayed at 54.5 units/ml glucoamylase activity and 12.3 units/ml pullulanase activity using 1% (w/v) pullulan as substrate.
• High dextrose syrups were prepared by digesting 50 ml samples of 30% DS enzyme liquified cornstarch (40 DE) in 0.05 M acetate at pH 4.2 in shake flasks for 24 hours at 50° C. with various amounts of coimmobilized glucoamylase-pullulanase composite thus prepared.
• the carbohydrate profiles are given in the following Table.
• the syrups thus obtained are higher in glucose and lower in isomaltose than those obtained in Example I.
• a combination of glucoamylase/pullulanase has a different hydrolysis profile from glucoamylase by itself, theoretically due to the combined action of glucoamylase and pullulanase.
• a 100 ml quantity of derivatized porous GDE as in Example I was used for immobilization.
• a solution was prepared by mixing one gram beta-amylase (Hi-Maltosin S) and 20 ml of pullulanase (Pulluzyme®750L, ABM Chemicals Limited of Woodley Stockport Cheshire, England) in 0.005 M acetate buffer at pH 5.5. The beta-amylase and pullulanase were then coimmobilized on the porous GDE by the method given in Example I.
• the high maltose syrups were produced by hydrolyzing 50 ml samples of 30% DS Maltrin-150 in 0.05 M acetate at pH 5.5 in shake flasks for 24 hours at 50° C. with various amounts of coimmobilized beta-amylase/pullulanase thus prepared.
• the HPLC sugar profiles of the products are given in the following Table.
• compositions of the high maltose syrup prepared by coimmobilized beta-amylase/pullulanase are better than those produced by immobilized beta-amylase alone (Example IV), i.e., higher in maltose and lower in higher molecular weight sugars.
• Example IV this is theoretically attributed to the combined action of Beta-amylase and pullulanase.
• the immobilized pullulanase was significantly more thermally stable than the soluble enzyme. After 0.5 hour, GDE immobilized pullulanase still retained over 50% activity where the soluble pullulanase was already below 20% activity. By 2 hours, GDE immobilized pullulanase still retained around 42% activity but soluble pullulanase had already gone down to 0% activity.
• One gram of lactase (20,000 units) from A. oryzae was dissolved in 500 ml of 0.02 M sodium phosphate buffer solution (pH 7.0) and immobilized to GDE by the same method given in Example I. Lactase activity was assayed at 50° C. and pH 4.5 using 5% (w/v) lactose as substrate. The released glucose was determined by the glucostrate method.
• One unit lactase activity is defined as the amount of enzyme which produced one micromole of glucose per minute at 50° C. at pH 4.5.
• the immobilized lactase thus obtained was assayed at 106.7 units per ml support.
• the degree of lactose hydrolysis was over 97% indicating that the immobilized lactase bound to GDE was rather active.
• the immobilization was carried out by the same method given in Example I.
• the immobilized transglucosidase thus obtained was assayed 2.6 units per ml support.
• Transglucosidase activity was assayed by a method based on the liquid chromatography quantitative measurement of a transglucosylic product, namely panose in an incubation mixture of enzyme and maltose at pH 4.5 and 60° C.
• One unit of transglucosidase activity is defined as the amount of enzyme which produced one micromole of panose per hour from 20% maltose solution at pH 4.5 and 60° C.
• Non-fermentable sugars (mainly panose and isomaltose) were produced by digesting 50 ml of 30% DS maltose solution (pH 4.5, 0.05 M acetate) in a shake flask with 10 ml of immobilized transglucosidase thus prepared for five days at 60° C. GC analysis of the product showed the following sugar profile: 28.3% glucose, 34.8% maltose, 7.4% isomaltose, 22.1% panose and 7.5% higher sugars. The total amount of non-fermentable sugars ( ⁇ 1-6 linkage) produced in this Example was about 37%.

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• 1985
  • 1985-09-23 US US06/779,053 patent/US4713333A/en not_active Expired - Lifetime
• 1986
  • 1986-09-12 DE DE8686112638T patent/DE3688493T2/de not_active Expired - Fee Related
  • 1986-09-12 EP EP86112638A patent/EP0216272B1/en not_active Expired - Lifetime
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• 1992
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